It has widely been known to configure that torque transmitted from drive wheels of a vehicle is not transmitted to a transmission gear device. For example, a vehicle that includes: an auxiliary transmission including plural transmission paths with different transmission gear ratios; and a clutch for connecting or blocking any of the transmission paths of an auxiliary transmission and a toroidal continuously variable transmission, in a torque transmission path between the toroidal continuously variable transmission and drive wheels is described in Japanese Patent Application Publication No. 2002-89706 (JP 2002-89706 A).
In addition, a control device described in JP 2002-89706 A is configured to actuate the clutch at a time that an internal combustion engine as a power source is stopped, control the auxiliary transmission to a neutral position regardless of a transmission gear step selected by a driver, and block transmission of torque between the toroidal continuously variable transmission and the drive wheels. According to a configuration described in JP 2002-89706 A, the transmission of the torque from the drive wheels to the toroidal continuously variable transmission is blocked in a state where the internal combustion engine is stopped. Thus, the toroidal continuously variable transmission in an unlubricated state can be prevented from being actuated by the torque from the drive wheels when the vehicle is towed. Therefore, durability of the toroidal continuously variable transmission can be improved.
Meanwhile, in recent years, due to requests of improved fuel economy, reduced exhaust gas of vehicles, and the like, types of control referred to as so-called idle stop control, stop and start control (hereinafter described as “S&S control”), and the like, which are control for stopping an internal combustion engine when the vehicle stops or a specified condition has been established during a travel, have been executed. It has been known to execute the S&S control, for example, in a case where the vehicle stops by following a traffic signal, in a case where depression of an accelerator pedal is cancelled by a driver and a vehicle speed is reduced, in a case where the depression of the accelerator pedal is cancelled in a state where the vehicle runs at a certain vehicle speed or higher, in a case where the driver depresses a brake pedal and the vehicle speed is thus reduced, and the like. That is, it is configured that, even when a main switch is in an ON state, the control for stopping the driving internal combustion engine is executed by establishment of the specified condition. In addition, the internal combustion engine is temporarily stopped by the S&S control. Thus, the internal combustion engine is possibly restarted thereafter by an acceleration request or the like.
In summary, the S&S control is control for stopping fuel supply to the internal combustion engine, stopping ignition of a gasoline engine, and the like. Accordingly, the internal combustion engine itself can be rotated under the S&S control. However, the transmission of the torque between the internal combustion engine and the drive wheels is blocked. It is because power is lost when the internal combustion engine is rotated during the S&S control, because drive torque fluctuates significantly when the internal combustion engine is restarted after an automatic stop, because a travel state of the vehicle and an operation state of the internal combustion engine differ when the S&S control is executed during the travel, and the like. For example, a clutch that is provided on an input side of the transmission gear device is disengaged, so as to block the transmission of the torque between the internal combustion engine and the drive wheels. The clutch only has to be provided in the torque transmission path between the internal combustion engine and the drive wheels, and may be provided on either the input side or an output side of the transmission gear device. In association with the stop of the internal combustion engine by the S&S control, various suggestions have conventionally been made for controlling the clutch.
However, it is not described in JP 2002-89706 A that the auxiliary transmission is brought into the neutral position when the main switch is in the ON state. Thus, there is still room for improvement of the control for engaging or disengaging the clutch in a state where the vehicle speed approximates zero and the internal combustion engine is stopped by bringing the auxiliary transmission into a neutral state in order to prepare for a case where the vehicle is towed and by bringing the auxiliary transmission into the neutral state in order to prepare for a restart of the internal combustion engine by the S&S control.
By the way, a vehicle, in which a continuously variable transmission section for continuously varying a transmission gear ratio and a stepped transmission section having one or plural fixed transmission gear ratios are provided in parallel, has been known. In this vehicle, plural torque transmission paths that stretch from a power source to the drive wheels are provided, and plural clutches for switching these transmission paths are provided. The torque transmission path that stretches from the power source to the drive wheel is configured to be switched to run through the transmission path including the continuously variable transmission section or the transmission path including the stepped transmission section by combinations of engaged states or disengaged states of the plural clutches. That is, it is configured to set connection or blockage of the torque transmission path, which regards to the torque transmission path between the power source and the drive wheels, the torque transmission path between the continuously variable transmission section and the power source or the drive wheels, the torque transmission path between the stepped transmission section and the power source or the drive wheels, and the like, by the combinations of the engaged states or the disengaged state of the plural clutches.
The configuration described in above-described JP 2002-89706 A is a structure in which the torque output from the toroidal continuously variable transmission is input to the auxiliary transmission, that is, a configuration in which the continuously variable transmission section and the stepped transmission section are arranged in series. Accordingly, in the vehicle including the transmission gear device in which those stepped transmission section and continuously variable transmission section are provided in parallel, there is still room for improvement of the control for bringing the transmission gear device into the neutral state by engaging or disengaging the clutches for switching the above-described transmission path when the control for stopping the internal combustion engine is executed.